Revert "HACK: mesa: Disable support for GLES >=3.1"

This reverts commit 21f05af49b22a1816f575f10a141eedaa25c8b10.

Reason for revert: merged to CL:748902

Original change's description:
> HACK: mesa: Disable support for GLES >=3.1
>
> Downgrade GLES2 version to 3.0 since advertising 3.1 triggers a number
> of test failures. Also disallow creating contexts newer than GLES 3.0 by
> the EGL_KHR_create_context extension.
>
> TODO: Revert once the Intel driver passes all GLES 3.1 tests.
>
> This is effectively a squash of following two CLs:
> https://chromium-review.googlesource.com/369180
> https://chromium-review.googlesource.com/377103
>
> BUG=b:30202361
> TEST=dEQP GLES 3.1 tests not failing and no regressions in other tests
> BUG=b:31041422
> TEST=Unity-based Crossy Roads and Dream Treats no longer crashing
> Signed-off-by: Kristian H. Kristensen <hoegsberg@chromium.com>
>
> BUG=b:33533853
> TEST=No CTS regressions on cyan and reef.
>
> Signed-off-by: Tomasz Figa <tfiga@chromium.org>
> Change-Id: I3541a75477e1f546b0c2aa81f4c8dcff801c9fd4
> Reviewed-on: https://chromium-review.googlesource.com/558140
> Reviewed-by: Chad Versace <chadversary@chromium.org>

BUG= b:30202361, b:31041422, b:33533853, b:68023297
TEST=`USE="-android_gles31 android_gles30" emerge-cave arc-mesa`
      and check corresponding file.
CQ-DEPEND=CL:748902, CL:749001
Change-Id: Ia2524ee7722e459fe84bcc09c7c6b576ba210901
Reviewed-on: https://chromium-review.googlesource.com/749002
Commit-Ready: Po-Hsien Wang <pwang@chromium.org>
Tested-by: Po-Hsien Wang <pwang@chromium.org>
Reviewed-by: Ilja H. Friedel <ihf@chromium.org>
diff --git a/src/egl/main/eglcontext.c b/src/egl/main/eglcontext.c
index 66ecb60..1a8e9bd 100644
--- a/src/egl/main/eglcontext.c
+++ b/src/egl/main/eglcontext.c
@@ -468,12 +468,6 @@
          break;
 
       case 3:
-         /* HACK: Disallow creating contexts newer than 3.0, since 3.1 triggers
-          * a number of test failures.
-          * (See: crbug.com/30202361, b/30202361, b/31041422) */
-         if (ctx->ClientMinorVersion > 0)
-            err = EGL_BAD_MATCH;
-
          /* Don't put additional version checks here.  We don't know that
           * there won't be versions > 3.0.
           */
diff --git a/src/mesa/main/version.c b/src/mesa/main/version.c
index 49f7f38..34f8bbb 100644
--- a/src/mesa/main/version.c
+++ b/src/mesa/main/version.c
@@ -593,13 +593,6 @@
       return;
 
    ctx->Version = _mesa_get_version(&ctx->Extensions, &ctx->Const, ctx->API);
-
-   /* HACK: Downgrade GLES2 version to 3.0 since advertising 3.1 triggers
-    * a number of test failures.
-    * (See: crbug.com/30202361, b/30202361, b/31041422) */
-   if (ctx->API == API_OPENGLES2 && ctx->Version > 30)
-      ctx->Version = 30;
-
    ctx->Extensions.Version = ctx->Version;
 
    /* Make sure that the GLSL version lines up with the GL version. In some